These devices are composed of a case or “generator,” including a power supply and the electronics of the device, and probes connected to the generator that are equipped with sensing/stimulation electrodes in contact with atrial and/or ventricular sites of the myocardium of a patient's heart.
As an alternative to or complementary with cardiac rhythm disorders, it was proposed to treat with bi-ventricular stimulation some myocardic contraction disorders observed among patients in cardiac insufficiency. These disorders can be spontaneous or induced by a traditional stimulation. The publication of J. C. Daubert et al., Stimucoeur, 25, n °3, pp. 170-176, gives a description of this. This bi-ventricular stimulation therapy often resulted in spectacular results for patients in class III cardiac insufficiency whose conditions were not improved by traditional treatments.
The first known devices of this type operated in synchronous stimulation, i.e., the two ventricular sites received a depolarization impulse at the same time with no inter-ventricular delay. More recent devices, such as those described, for example, in EP-A-1 108 446 and its counterpart U.S. Pat. No. 6,556,866 (which U.S. patent is incorporated herein by reference), both assigned herewith to ELA Médical, Montrouge, France, instead operate in a synchronous and controlled mode, by applying a variable inter-ventricular delay (DIV) between two stimulations, adjusted so as to resynchronize contraction of the ventricles with fine optimization of the hemodynamic state of the patient. The devices used currently for this purpose are “multisite” prostheses in which electrodes are placed in a plurality of distinct sites comprising the right and left ventricular sites and at least one atrial site. The devices can also be of the “triple chamber” (double ventricular stimulation and right atrial detection/stimulation) or “quadruple chamber” (double ventricular stimulation and double atrial detection/stimulation) types. EP-A-0 925 806 and its counterpart, U.S. Pat. No. 6,253,106 (which U.S. patent is incorporated herein by reference), both assigned herewith to ELA Médical, describe such multisite devices, comprising in particular means for selecting a stimulation configuration best suited for the patient.
The starting point of the present invention is the observation that the majority of patients receiving such implanted multisite devices typically present a normal atrio-ventricular conduction (where each atrial event is followed by an associated spontaneous ventricular depolarization) and therefore do not have a standard indication for implantation of a pacemaker. The triple or quadruple chamber multisite devices used for this purpose, when suitably parameterized to ensure a bi-ventricular stimulation, operate satisfactorily on a clinical level. But such devices are relatively sophisticated and therefore can be expensive and difficult to program, while at the same time a number of functions they are capable of performing go unused.